1) Disk file system 
StegFS is a free file system for Linux. It is licensed under the GPL. It was principally developed by Andrew D. McDonald and Markus G. Kuhn. It is a steganographic file system based on the ext2 filesystem. The last version of StegFS is 1.1.4, released February 14, 2001. This is a development release, with known bugs, such as a file corruption bug....